Single or Dual Sided Power Meter

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astro drive chain
Posts: 1
Joined: Sun Sep 02, 2018 12:12 am

Single or Dual Sided Power Meter

Post by astro drive chain »

I understand that to have an accurate CdA measurement it necessary to have a dual sided power meter - so to negate any right to left leg bias in power measurement.

However, I am not really that interested in obtaining an absolute accurate CdA measurements (within reasons). I just want to use my current TT setup at an outdoor velodrome as a referenced benchmark and investigate the change in CdA as i make adjustments. A bias in direct power measurement and CdA calculation should not impact this application.

So in that sense i am more reliant on precision of a single sided power meter. If a single sided power meter is in fact less precise (higher variance) then couldn't i just sample more data (ride for a longer time) so the measured average will reflect the true (biased) value.

Also, you have stated that the CdA measurement from the Aeropod is precise to three decimal places. What kind of changes in CdA should I expect from common practical changes made to a TT position or equipment? Will there be a significant jump in the first, second or third decimal place (1/10, 1/100 or 1/1000 CdA unit) in the CdA measurement? I had a look at some literature and it seems that a TT helmet improvement can result in an approximate increase of 0.03 CdA - which is well within the 0.000 precision specified for Aeropod measurement.
Velocomp
Velocomp CEO
Posts: 7803
Joined: Fri Jan 11, 2008 8:43 am

Re: Single or Dual Sided Power Meter

Post by Velocomp »

You're correct that relative measurements can be made with a one-side power meter. Just make sure you are consistent in your left/right pedaling effort. AeroPod will assume there is 100% consistency in the left/right split...

In our testing we can detect CdA changes from different aero helmets. Hopefully your aero helmet will decrease, not increase, your CdA :-)

We provide some ranges in the AeroPod Instructions.
John Hamann
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